Disk drives typically comprise a number of disks with a head actuated over each of the top and bottom disk surface. Each head is connected to a distal end of an actuator arm which is rotated about a pivot by a voice coil motor (VCM) to position the head radially over the disk. The disk comprises a plurality of radially spaced, concentric tracks for recording user data sectors and servo sectors. The servo sectors comprise head positioning information (e.g., a track address) which is read by the head and processed by a servo control system to control the velocity of the actuator arm as it seeks from track to track.
A disk drive also typically comprises a preamp circuit for amplifying the read signal emanating from one of the heads during read operations, and for applying a write current to one of the heads during write operations. The preamp circuit is typically implemented as a separate integrated circuit mounted to the actuator arm assembly and connected through a flex circuit to a printed circuit board (PCB) mounted to a base of the disk drive. Additional control circuitry mounted on the PCB processes the preamplified read signal during read operations to demodulate the data recorded on the disk, as well as generates a data modulated write signal applied to the preamp circuit during write operations.